Retractable index pins and methods of operating thereof

ABSTRACT

Provided are self-retractable centering assemblies and methods of using these assemblies for alignment of parts having determinant assembly alignment holes. An assembly includes a center pin having a threaded portion threadably engaging a drive component. The assembly also includes a puller bushing rotatably coupled to the drive component. The center pin protrudes through the puller bushing and can slide with respect to the puller bushing when the drive component is rotated relative to the center pin. The sliding distance is controlled by a limiter disposed within the cavity of the puller bushing. During operation, a portion of the center pin extends from the puller bushing and is inserted into alignment holes of parts being aligned. The drive component is rotated relative to the center pin resulting in the center pin being pulled out of the alignment holes while the puller bushing is being pressed against the parts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/218,346, entitled: “RETRACTABLE INDEX PINS AND METHODS OF OPERATINGTHEREOF” filed on Jul. 25, 2016, which is incorporated herein byreference in its entirety for all purposes.

BACKGROUND

Many conventional alignment methods utilize pins inserted intodeterminant assembly alignment holes of two or more parts while theseparts are being aligned. The tight fit of these pins in the holesensures precise alignment of the holes and, as a result, precisealignment of the parts. However, removal of these pins from thealignment holes can be challenging because of the tight fit. Variousdesigns with different levels of success have been tried. For example,aircraft manufacturing typically uses L-shaped pins. An L-shaped pinincludes a handle extending perpendicular to the insertion portion. Thehandle is used during installation and removal of these pints. However,even with the available handles, the L-shaped pins are being manuallyremoved using, for example, a hammer. Hammering is needed to overcomethe high friction forces between the pins and alignment holes associatedwith the tight fit. Hammering may be undesirable for some parts, such ascomposites, because of highly concentrated force spikes. Furthermore,hammering may not be desirable from ergonomic perspectives. What isneeded are alignment pins and pin removal methods exerting lower andmore uniform stress on aligned parts.

SUMMARY

The following presents a simplified summary of the disclosure in orderto provide a basic understanding of certain embodiments of thisdisclosure. This summary is not an extensive overview of the disclosure,and it does not identify key and critical elements of the presentdisclosure or delineate the scope of the present disclosure. Its solepurpose is to present some concepts disclosed herein in a simplifiedform as a prelude to the more detailed description that is presentedlater.

Provided are self-retractable centering assemblies and methods of usingthese assemblies for alignment of parts having determinant assemblyalignment holes. An assembly includes a center pin having a threadedportion threadably engaging a drive component. The center pin may bealso referred to as an index pin. The assembly also includes a pullerbushing rotatably coupled to the drive component. The center pinprotrudes through the puller bushing and can slide with respect to thepuller bushing when the drive component is rotated relative to thecenter pin. The sliding distance is controlled by a limiter disposedwithin the cavity of the puller bushing. During operation, a portion ofthe center pin extends from the puller bushing and is inserted intoalignment holes of parts being aligned. The drive component is rotatedrelative to the center pin resulting in the center pin being pulled outof the alignment holes while the puller bushing is being pressed againstthe parts.

In some embodiments, a self-retractable centering assembly comprises acenter pin, a puller bushing, a drive component, and a limiter. Thecenter pin comprises a threaded portion. The puller bushing comprises acavity. The center pin protrudes through the cavity of the pullerbushing. The center pin is slidable relative the puller bushing alongthe center axis of the center pin. The drive component is rotatablycoupled to the puller bushing. The drive component threadably engagesthe threaded portion of the center pin such that rotation of the drivecomponent relative to the center pin and around the center axis of thecenter pin slides the center pin relative to drive component and, as aresult, relative to the puller bushing. The limiter is disposed withinthe cavity of the puller bushing and limiting the sliding distance ofthe center pin relative to the puller bushing. Specifically, the limitermay limit how much the center pin extends out of the puller bushing inits extended state. Furthermore, the limiter may limit how much thecenter pin retracts into the puller bushing when it moves into itsretracted state. The travel of the center pin between its fullyretracted state and its fully extended state is referred to as a slidingdistance.

In some embodiments, the limiter is a stop nut threadably engaging thethreaded portion of the center pin. Alternatively, the limiter may be acollar of the center pin. Furthermore, the limiter may be a slot keyprotruding into a slot of the center pin. The slot key may be a Woodruffkey. In some embodiments, the limiter is a transverse pin protrudingthrough the center pin in a direction perpendicular to the center axisof the center pin and extending away from the center pin. In theseembodiments, the limiter may be constrained by internal surfaces of thecavity. For example, front and back sides of the cavity (defined alongthe center axis) may be operable as positive stops for the limiter.Alternatively, other components may be used as stops. For example, thelimiter may be a combination of a sliding planar surface of the centerpin and a protrusion fixed relative the puller bushing. The slidingplanar surface extends parallel to the center axis of the center pin.

In some embodiments, the center pin is not rotatable relative to thepuller bushing. For example, the self-retractable centering assembly mayfurther comprise a coupling component non-rotatably engaging the pullerbushing and the center pin. Specifically, the coupling component maynon-rotatably engage the center pin through an end componentnon-rotatably connected to the end of the center pin opposite to theinsertion portion of the center pin.

In some embodiments, the center pin comprises a collar disposed withinthe cavity such that both the collar and the cavity of the pullerbushing have non-circular cross-sectional shapes within a planeperpendicular to the center axis of the center pin. As a result of thesenon-circular cross-sectional shapes the center pin is not rotatablerelative to the puller bushing. Specifically, the cavity may have anelliptical cross-sectional shape within the plane perpendicular to thecenter axis of the center pin. In these embodiments, the collar may bealso operable as a limiter.

In some embodiments, the self-retractable centering assembly furthercomprises a slot key protruding into a slot of the center pin and into asliding slot of the puller bushing. This combination of the slot key andthe slot results in the center pin being not rotatable relative to thepuller bushing. As noted above, a combination of the slot key and theslot may be operable as a limiter as well.

In some embodiments, the self-retractable centering assembly furthercomprises a transverse pin protruding through the center pin in adirection perpendicular to the center axis of the center pin. Thetransverse pin extends away from the center pin and into two slots ofthe puller bushing. This combination of the transverse pin and the twoslots results in the center pin being not rotatable relative to thepuller bushing. As noted above, a combination of the transverse pin andthe two slots may be operable as a limiter as well.

In some embodiments, the self-retractable centering assembly furthercomprises a sliding planar surface of the center pin and a protrusionfixed relative the puller bushing. The sliding planar surface extendsparallel to the center axis of the center pin. This combination of thesliding planar surface and the protrusion results in the center pinbeing not rotatable relative to the puller bushing. As noted above, acombination of the sliding planar surface and the protrusion may beoperable as a limiter as well.

In some embodiments, the drive component is rotatably coupled to thepuller bushing using a thrust bearing. Specifically, the thrust bearingmay be disposed between the drive component and the puller bushing andallow for the drive component relative the puller bushing while exertinga force onto the puller bushing in the direction along the center axisof the center pin.

In some embodiments, the center pin comprises an insertion portion. Theinsertion point protracts out of the cavity and retracts into the cavityas the center pin slides relative the puller bushing or, morespecifically, as the drive component rotates relative to the center pin.The insertion portion of the center pin comprises a tip, which may havea tapered shape. This tapered shape allows insertion of the center pininto initially misaligned holes.

In some embodiments, the self-retractable centering assembly furthercomprises a surface engaging component disposed on a side of the pullerbushing opposite of the drive component. The surface engaging componentmay comprise polymer. The surface engaging component may be used toprotect a part when the puller bushing is pressed against the partduring extraction of the center pin. The side of the puller bushingopposite of the drive component may extend substantially perpendicularto the center axis of the center pin.

Provided also is a method of aligning a first part comprising a firstdeterminant assembly alignment hole relative to a second part comprisinga second determinant assembly alignment hole. In some embodiments, themethod comprises inserting a center pin of a self-retractable centeringassembly into the first determinant assembly alignment hole and thesecond determinant assembly alignment hole. The method may also compriseretracting the center pin from the first determinant assembly alignmenthole and the second determinant assembly alignment hole. This retractingof the center pin may comprise rotating a drive component of theself-retractable centering assembly relative to the center pin andaround a center axis of the center pin thereby sliding the center pinrelative to a puller bushing of a self-retractable centering assembly.The puller bushing may be being pressed against the first part whileretracting the center pin.

In some embodiments, after inserting the center pin into the firstdeterminant assembly alignment hole and into the second determinantassembly alignment hole, a center axis of first determinant assemblyalignment hole coincides with a center axis of the second determinantassembly alignment hole.

In some embodiments, rotating the drive component relative to the centerpin comprises supporting the puller bushing. For example, the pullerbushing may be supported by an operator using a wrench or some othersuitable tool. In some embodiments, the puller bushing is supportedusing a coupling component of the self-retractable centering assembly.In these embodiments, the puller bushing is supported together with thecenter pin.

In some embodiments, the drive component rotates relative to the pullerbushing while retracting the center pin. However, the puller bushing maynot rotate relative to the center pin during this operation.

In some embodiments, the center pin does not rotate within the firstdeterminant assembly alignment hole relative to the first part or withinthe second determinant assembly alignment hole relative to the secondpart while the center pin being retracted from the first determinantassembly alignment hole and from the second determinant assemblyalignment hole. Furthermore, the puller bushing may be stationaryrelative to the first part as the center pin being retracted from thefirst determinant assembly alignment hole and from the seconddeterminant assembly alignment hole. Specifically, the puller bushingmay not rotate relative to the first part. Furthermore, the pullerbushing does not move linearly along the center axis during thisoperation. Alternatively, the puller bushing rotates relative to thefirst part. In these embodiments, the center pin may also rotate withinthe first determinant assembly alignment hole relative to the first partor within the second determinant assembly alignment hole relative to thesecond part as the center pin being retracted from the first determinantassembly alignment hole and the second determinant assembly alignmenthole.

In some embodiments, the method further comprises, after retracting thecenter pin, increasing the size of at least one of the first determinantassembly alignment hole and the second determinant assembly alignmenthole. In some embodiments, the size of both holes is increased. In thesame or other embodiments, the method may comprise, after retracting thecenter pin, installing a fastener into the first determinant assemblyalignment hole and the second determinant assembly alignment hole.

These and other embodiments are described further below with referenceto the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of two parts being aligned using aself-retractable centering assembly, in accordance with someembodiments.

FIG. 1B is another schematic illustration of two parts being alignedusing a self-retractable centering assembly prior to retracting thecenter pin of the assembly from the determinant assembly alignment holesof the parts, in accordance with some embodiments.

FIG. 1C is a schematic illustration of the two parts of FIG. 1B afterretracting the center pin of the assembly from the determinant assemblyalignment holes of the two parts, in accordance with some embodiments.

FIG. 2A is a schematic side view of a self-retractable centeringassembly, in accordance with some embodiments.

FIG. 2B is a schematic cross-sectional view of the self-retractablecentering assembly of FIG. 2A illustrating various internal features ofthe assembly, in accordance with some embodiments.

FIG. 2C is a schematic perspective view of the self-retractablecentering assembly of FIG. 2A with an optional coupling component, inaccordance with some embodiments.

FIG. 2D is a schematic cross-sectional view of the self-retractablecentering assembly of FIG. 2B illustrating engagement between thecoupling component and other components of the assembly, in accordancewith some embodiments.

FIG. 3A is a schematic side view of a self-retractable centeringassembly, in accordance with some embodiments.

FIGS. 3B and 3C are schematic cross-sectional views of theself-retractable centering assembly of FIG. 3A illustrating variousinternal features of the assembly, in accordance with some embodiments.

FIG. 4A is a schematic side view of a self-retractable centeringassembly, in accordance with some embodiments.

FIGS. 4B and 4C are schematic cross-sectional views of theself-retractable centering assembly of FIG. 4A illustrating variousinternal features of the assembly, in accordance with some embodiments.

FIG. 5A is a schematic side view of a self-retractable centeringassembly, in accordance with some embodiments.

FIGS. 5B and 5C are schematic cross-sectional views of theself-retractable centering assembly of FIG. 5A illustrating variousinternal features of the assembly, in accordance with some embodiments.

FIG. 6A is a schematic side view of a self-retractable centeringassembly, in accordance with some embodiments.

FIGS. 6B and 6C are schematic cross-sectional views of theself-retractable centering assembly of FIG. 6A illustrating variousinternal features of the assembly, in accordance with some embodiments.

FIG. 7 is a process flowchart corresponding to a method of aligning twoparts using a self-retractable centering assembly, in accordance withsome embodiments.

FIGS. 8A-8I are schematic cross-sectional views of the two parts atvarious stages of aligning these parts using a self-retractablecentering assembly, in accordance with some embodiments.

FIG. 9 is a block diagram of aircraft production and service methodologythat may utilize methods and assemblies described herein.

FIG. 10 is a schematic representation of the aircraft produced utilizingmethods and assemblies described herein.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented concepts. Thepresented concepts may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail so as to not unnecessarily obscure thedescribed concepts. While some concepts will be described in conjunctionwith the specific embodiments, it will be understood that theseembodiments are not intended to be limiting. On the contrary, it isintended to cover alternatives, modifications, and equivalents as may beincluded within the spirit and scope of the present disclosure asdefined by the appended claims.

Introduction

Different parts may be precisely aligned using determinant assemblyalignment holes provided in these parts as well as center pinsprotruding into these alignment holes. However, retracting the centerpins from the alignment holes can be challenging because of highfriction forces between the center pins and the alignment holes, asnoted above. Provided are self-retractable centering assemblies andmethods of using these assemblies for parts' alignment. An assemblyincludes a center pin having a threaded portion threadably engaging adrive component. This threaded portion is used for extracting the centerpin from alignment holes. Specifically, the drive component is rotatedrelative to the center pin and causes the center pin to slide linearlyalong the center axis of the center pin with respect to the drivecomponent. The assembly includes a puller bushing rotatably coupled tothe drive component. The center pin protrudes through the puller bushingand can slide with respect to the puller bushing when the drivecomponent is rotated relative to the center pin. The puller bushing isdisposed between the drive component and the parts being aligned and ispressed against these parts while retracting the center pin. The pullerbushing allows for the drive component to rotate relative to the parts.

The sliding distance of the center pin is controlled by a limiter, whichmay be disposed within the cavity of the puller bushing. Duringoperation, a portion of the center pin extends from the puller bushingand is inserted into alignment holes of parts being aligned. The drivecomponent is rotated relative to the center pin resulting in the centerpin being pulled out of the alignment holes while the puller bushing isbeing pressed against the parts. The total travel of the center pinbetween its retracted position and its extended position is defined asthe sliding distance. The limiter allows to control the insert depth ofthe center pin into determinant assembly alignment holes, which may helpto avoid damaging the parts being aligned. Furthermore, the limiter alsoallows to control when the puller bushing can be separated from theparts. For example, the puller bushing may be required to contact thepart until the center pin is in its complete retracted position.

The presented self-retractable centering assembly allows for simpleremoval of the center pin without using a hammer or other impact toolsthereby preserving integrity of parts being aligned as well as integrityof the self-retractable centering assembly. The center pin retraction isachieved by rotating the drive component relative to the center pin.

FIG. 1A is a schematic illustration of two parts 10 a and 10 b beingaligned using self-retractable centering assembly 100, in accordancewith some embodiments. Other embodiments are also within the scope. Inthe illustrated embodiments, first part 10 a may be a pressure bulkheador, more specifically, an aft frame of the bulkhead ring of an aircraft.Second part 10 b may a forward frame of the aircraft. In this example,center pin 110 of self-retractable centering assembly 100 protrudesthrough both first part 10 a and second part 10 b. One having ordinaryskills in the art would understand that self-retractable centeringassembly 100 may be used to align any two or more parts havingdeterminant assembly alignment holes and are not limited to the types ofparts 10 a and 10 b shown in FIG. 1A. In general, any types of partshaving determinant assembly alignment holes may be aligned usingself-retractable centering assembly 100. These parts and alignment maybe used for any applications. Furthermore, while only oneself-retractable centering assembly 100 is shown in FIG. 1A, one havingordinary skills in the art would understand that two or moreself-retractable centering assemblies 100 may be used to aligned thesame set of parts. The set of parts may include two, three, or moreparts.

FIG. 1B is another schematic illustration of two parts 10 a and 10 bbeing aligned using self-retractable centering assembly 100 prior toretracting center pin 110 of assembly 100 from determinant assemblyalignment holes 12 a and 12 b of parts 10 a and 10 b, in accordance withsome embodiments. In these embodiments, parts 10 a and 10 b are aligned.Center pin 110 may be tightly fit in determinant assembly alignmentholes 12 a and 12 b and its removal from determinant assembly alignmentholes 12 a and 12 b may require a significant force along center axis119 of center pin 110. This force is achieved by applying torque todrive component 130 and rotating drive component 130 relative to centerpin 110. Center pin 110 may be supported from rotation by variousfeatures of self-retractable centering assembly 100 further describedbelow. Rotation of drive component 130 relative to center pin 110linearly advances center pin 110 relatively to drive component 130. Inother words, rotation direction 20 translates into sliding direction 30.Since drive component 130 is supported by puller bushing 120 relative toparts 10 a and 10 b (in the direction along center axis 119), the linearadvancement of center pin 110 relative to drive component 130 alsoadvances center pin 110 relative to parts 10 a and 10 b effectivelyretracting center pin 110 from determinant assembly alignment holes 12 aand 12 b. FIG. 1C is a schematic illustration of the same two parts 10 aand 10 b as in FIG. 1B after retracting center pin 110 from determinantassembly alignment holes 12 a and 12 b. The state of self-retractablecentering assembly 100 shown in FIG. 1B may be referred to an extendedstate, while the state shown in FIG. 1C may be referred to a retractedstate.

Examples of Self-Retractable Centering Assemblies

FIG. 2A is a schematic side view of self-retractable centering assembly100, in accordance with some embodiments. Self-retractable centeringassembly 100 comprises center pin 110, puller bushing 120, and drivecomponent 130. Drive component 130 is rotatably coupled to pullerbushing 120 using, for example, thrust bearing 150. Specifically, thrustbearing 150 may be disposed between drive component 130 and pullerbushing 120 as, for example, shown in FIG. 2A. Other types of rotationalslip couplings between drive component 130 and puller bushing 120 arealso within the scope. This coupling allows for puller bushing 120 tosupport force along center axis 119 of center pin 110 exerted by drivecomponent 130 during operation self-retractable centering assembly 100while allowing drive component 130 to rotate relative to puller bushing120.

Center pin 110 is slidable relative to puller bushing 120 between itsextended state and retracted state with the extended state shown in FIG.2A. Furthermore, center pin 110 comprises insertion portion 114. In theextended state, insertion portion 114 extends outside of puller bushing120. In the retracted state, at least some of insertion portion 114 isretracted into puller bushing 120 as, for example, shown in FIG. 1B.Insertion portion 114 may be inserted, for example, into determinantassembly alignment holes 12 a and 12 b of parts 10 a and 10 b whilealigning these parts as further described below with reference to FIG. 7and FIGS. 8A-8I.

As shown in FIG. 2A, self-retractable centering assembly 100 may alsoinclude end component 140. End component 140 may be non-rotatablycoupled to center pin 110 and may be used for supporting center pin 110while, for example, rotating drive component 130. For example, endcomponent 140 may have a shape of a hexagonal nut and a socket, wrench,or other suitable tool may be used to support end component 140 (andcenter pin 110) from rotation. Alternatively, other features ofself-retractable centering assembly 100 may be use for supporting centerpin 110.

As shown in FIG. 2A, self-retractable centering assembly 100 may alsoinclude surface engagement component 170. Surface engaging component 170disposed on side 124 of puller bushing 120 opposite of drive component130. This side 124 may extend substantially perpendicular to center axis119 of center pin 110 and may be substantially planar. Alternatively,side 124 may be profiled similar to the side of a part facing pullerbushing 120. Surface engaging component 170 may comprise polymer orother suitable materials. Surface engaging component 170 may be used toprotect the surface of the part facing puller bushing 120 and moreuniformly distribute the pressure applied on that surface by pullerbushing 120 during operation of self-retractable centering assembly 100.

Some components and features of self-retractable centering assembly 100may be disposed inside other component or hidden by other component.Referring to FIG. 2B, puller bushing 120 comprises cavity 122. Centerpin 110 protrudes through cavity 122 of puller bushing 120. Center pin110 may be slidable within cavity 129 relative puller bushing 120 alongcenter axis 119 of center pin 110. This sliding features allows centerpin 110 to move between its extended state and retracted state asdescribed above with reference to FIGS. 1B and 1C.

Referring to FIG. 2B, center pin 110 comprises threaded portion 112.Drive component 130 threadably engages threaded portion 112 of centerpin 110 such that rotation of drive component 130 relative to center pin110 and around center axis 119 of center pin 110 slides center pin 110relative to drive component 130 and also relative to puller bushing 120.

Drive component 130 may also rotate relative to puller bushing 120.However, their axial position along center axis 119 may remainsubstantially the same during operation of self-retractable centeringassembly 100. As such, any axial movement of drive component 130relative to center pin 110 may cause similar axial movement of pullerbushing 120, also relative to center pin 110. When puller bushing 120 ispositioned against parts, this axial movement may be used to retractcenter pin 110 from the parts. In other words, puller bushing 120 isused as a support for drive component 130 that allows for drivecomponent 130 to rotate at least with respect to center pin 110 and, insome embodiments, with respect to parts that are aligned usingself-retractable centering assembly 100.

Self-retractable centering assembly 100 may also comprise limiter 160disposed within cavity 122 of puller bushing 120. Limiter 160 is used tolimit sliding distance 103 of center pin 110 relative to puller bushing120. As noted above, sliding distance 103 is the distance between theprotracted position and retracted position. As such, limiter 160 mayalso define the protracted position and also the retracted position ofcenter pin 110.

Referring to FIG. 2B, limiter 160 may be stop nut 160 a threadablyengaging threaded portion 112 of center pin 110. Stop nut 160 a may notrotate relative to center pin 110 when drive component 130 rotatesrelatively center pin 110. Thereby, the linear position of stop nut 160a on center pin 110 may be preserved during operation ofself-retractable centering assembly 100. In fact, stop nut 160 a, centerpin 110, and puller bushing 120 may not rotate relative to each otherduring operation of self-retractable centering assembly 100. Forexample, the internal surface of cavity 122 may engage the surface ofstop nut 160 a and prevent stop nut 160 a from rotating around centeraxis 119. It should be noted that stop nut 160 a may slide within cavity122, and this sliding feature may define sliding distance 103. In fact,sliding distance 103 may be equal to the length of cavity 122 (definedalong venter axis 119) less the thickness of stop nut 160 a (defined inthe same direction), which may be represented by the following formula:D_(sliding)=Length_(cavity)−Thickness_(stop nut).

Referring to FIG. 3B that shows a cross-section of self-retractablecentering assembly 100 in FIG. 3A, limiter 160 may be collar 160 b ofcenter pin 110. This collar 160 b may be monolithic with the rest ofcenter pin 110. For example, collar 160 b may be machined duringfabrication of center pin 110. Similar to the example of stop nut 160 adescribed above with reference to FIG. 2B, collar 160 b may slide withincavity 122 and this sliding may define sliding distance 103. In fact,sliding distance 103 may be equal the length of cavity 122 defined alongventer axis 119 less the thickness of collar 160 b defined in the samedirection. However, in this example, threaded portion 112 may be shorterthan in the example shown in FIG. 2B.

Referring briefly to FIGS. 3A and 3B, puller bushing 120 may includeplanar engagement surfaces 123. For example, two planar engagementsurfaces 123 may be used in order to support puller bushing 120 with awrench or any other suitable tool. As shown in FIG. 3A, planarengagement surfaces 123 may be parallel to each other and also parallelto center axis 119 of center pin 110.

Referring to FIGS. 4B and 4C that shows a cross-section ofself-retractable centering assembly 100 in FIG. 4A, limiter 160 may beslot key 160 c protruding into slot 160 d of center pin 110. One exampleof slot key 160 c is Woodruff key 160 e. However, other types of slotkeys are also within the scope. Slot key 160 c may operate similar tostop nut 160 a or collar 160 b even though it extends only in onedirection away from center axis 119. Slot key 160 c may slide betweenedges of cavity 122. In some embodiments, cavity 122 may includepositive stops that limit sliding distance 103 of slot key 160 c as, forexample, is shown in FIG. 4B. In this example, the positive stops aretransverse pins 121 a and 121 b protruding into openings in pullerbushing 120 as schematically shown in FIG. 4B.

Referring to FIG. 5B that shows a cross-section of self-retractablecentering assembly 100 in FIG. 5A, limiter 160 may be transverse pin 160f protruding through center pin 110 in direction 161 perpendicular tocenter axis 119 of center pin 110. End of transverse pin 160 f extendaway from center pin 110 and may limit sliding distance 103 whenencounter positive stops or other components on its way. For example,FIG. 5B illustrates two other transverse pins 121 a and 121 b supportedby puller bushing 120 and operable as positive stops.

Referring to FIG. 6B that shows a cross-section of self-retractablecentering assembly 100 in FIG. 6A, limiter 160 may be a combination ofsliding planar surface 160 g of center pin 110 and protrusion 160 hfixed relative puller bushing 120. Sliding planar surface 160 g extendsparallel to center axis 119 of center pin 100. Sliding distance 103 islimited by the length of sliding planar surface 160 g defined in thedirection of center axis. The end of sliding planar surface 160 g act aspositive stops.

In some embodiments, center pin 110 is not rotatable relative to pullerbushing 120. In these embodiments, puller bushing 120 may be used toprevent center pin 110 from rotation (when drive component 130 isrotated) or to rotate center pin 110 at a different speed and/ordifferent direction than drive component 130. It should be noted thateven though center pin 110 may not rotate relative to puller bushing120, it can still slide relative to puller bushing 120 in the directionof center axis 119.

In order to prevent center pin 110 from rotating relative to pullerbushing 120 (maintaining their angular orientation), self-retractablecentering assembly 100 may further comprise coupling component 180non-rotatably engaging puller bushing 120 and center pin 110 as, forexample, shown in FIG. 2C. Specifically, coupling component 180 mayinclude first engagement component 182, second engagement component 184,and handle 186 extending between and connecting first engagementcomponent 182 and second engagement component 184. First engagementcomponent 182 may non-rotatably engage puller bushing 120. It should benoted that this non-rotatable engagement allows first engagementcomponent 182 to slide relative to puller bushing 120 during operationof self-retractable centering assembly 100 (e.g., when extracting centerpin 110). First engagement component 182 may be in the form of a fork,ring, or any other suitable shape.

Second engagement component 184 may non-rotatably engage center pin 110,for example, through end component 140. As noted above, end component140 is non-rotatably connected to the end of center pin 110 opposite toinsertion portion 114 of center pin 114. End component 140 may be a nutor any other suitable device. FIG. 2D is a cross-sectionalrepresentation of one example of second engagement component 184non-rotatably engaging end component 140. In this example, end component140 is a hexagonal nut (hex nut), while second engagement component 184is a tubular hexagonal socket.

In addition to maintaining the angular position of center pin 110 andpuller bushing 120, coupling component 180 allows the operator tosupport entire self-retractable centering assembly 100 with one hand.Referring to FIG. 2C, drive component 130 remains accessible and can beturned relative to coupling component 180 with a wrench or any othersuitable tool. Rotation of drive component 130 relative to couplingcomponent 180 will cause center pin 110 to slide relative to pullerbushing 120. In some embodiments, this sliding of center pin 110 willalso cause coupling component 180 to slide relative to puller bushing120.

Another approach to prevent center pin 110 from rotating relative topuller bushing 120 (maintaining their angular orientation) is using oneor more features provided directly on center pin 110 and puller bushing120. Referring to FIGS. 3B and 3C, center pin 110 may comprise collar160 b disposed within cavity 122. Both collar 160 b and cavity 122 havenon-circular cross-sectional shapes within the plane (Y-Z) perpendicularto center axis 119 of center pin 110 such that the largestcross-sectional dimension of collar 160 b is greater than the smallestcross-sectional dimension of cavity 122. One example of the non-circularcross-sectional shapes are shown in FIG. 3C. Specifically, in thisexample, collar 160 b has flat portion 161 that contact planar portion123 of puller bushing 120 and prevent rotation of center pin 110relative to puller bushing 120. In some embodiments, cavity 122 may havean elliptical cross-sectional shape within a plane perpendicular tocenter axis 119 of center pin 110. Collar 160 b may have a similarelliptical cross-sectional shape. However, other cross-sectional shapesare also within the scope.

Referring to FIGS. 4B and 4C, self-retractable centering assembly 100may comprise slot key 160 c protruding into slot 160 d of center pin 110and into sliding slot 120 a of puller bushing 120. Slot key 160 c may beslidable within sliding slot 120 a. In other words, slot key 160 c and,as a result, center pin 110 can slide relative to puller bushing 120. Atthe same time, this combination of slot key 160 c and slot 160 d resultsin center pin 110 being not rotatable relative to puller bushing 120.

Referring to FIGS. 5B and 5C, self-retractable centering assembly 100may comprise transverse pin 160 f protruding through center pin 110 inthe direction (Y direction) perpendicular to center axis 119 of centerpin 110. Transverse pin 160 f extends away from center pin 110 and intotwo slots 120 b of puller bushing 120. Transverse pin 160 f may slidewithin two slots 120 b relative to puller bushing 120 and, as a result,center pin 110 may slide relative to puller bushing 120. At the sametime, this combination of transverse pin 160 f and two slots 120 bresults in center pin 110 being not rotatable relative to puller bushing120.

Referring to FIGS. 6B and 6C, self-retractable centering assembly 100may comprise sliding planar surface 160 g of center pin 110 andprotrusion 160 h fixed relative puller bushing 120. Sliding planarsurface 160 g extends parallel to center axis 119 of center pin 100.This combination of sliding planar surface 160 g and protrusion 160 hresults in center pin 110 being not rotatable relative to puller bushing120.

Examples of Methods Using Self-Retractable Centering Assemblies

FIG. 7 is a process flowchart corresponding to method 700 of aligningtwo parts 10 a and 10 b using self-retractable centering assembly 100,in accordance with some embodiments. Different stages of method 700 areschematically illustrated in FIGS. 8A-8I. Examples of self-retractablecentering assembly 100 are described above.

Method 700 may commence with pre-aligning first part 10 a relative tosecond part 10 b during optional operation 710. First part 10 a maycomprise first determinant assembly alignment hole 12 a, while secondpart 10 b comprises second determinant assembly alignment hole 12 b.This pre-alignment ensures that center pin 110 of self-retractablecentering assembly 100 can be inserted in both determinant assemblyalignment holes 12 a and 12 b. It may be referred to as rough alignment.Further alignment is provided when center pin 110 is inserted in bothdeterminant assembly alignment holes 12 a and 12 b. The required levelof the pre-alignment depends on the design of center pin 110 or, morespecifically, the design of tip 116 of its insertion portion 114. Insome embodiments, tip 116 has a tapered shape to allow for less precisepre-alignment. FIG. 2A illustrates first part 10 a and second part 10 bprior to operation 710, while FIG. 2A illustrates these parts 10 a and10 b after operation 710. For example, after pre-alignment, center axis14 a of first determinant assembly alignment hole 12 a is at leastwithin the boundaries of second determinant assembly alignment hole 12b.

Method 700 may proceed with inserting center pin 110 of self-retractablecentering assembly 100 into first determinant assembly alignment hole 12a and into second determinant assembly alignment hole 12 b duringoperation 720. In some embodiments, center pin 110 may be in itsextended state during this operation 720. For example, center pin 110may be pressed, hammered, or otherwise inserted into determinantassembly alignment holes 12 a and 12 b. Alternatively, center pin 110may be extended from puller bushing 120 as a part of operation 720.

The material of center pin 110 may be such that center pin 110 maintainsits shape during insertion and retraction operations without damagingparts 10 a and 10 b. In general, the material of center pin 110 may beharder and mechanically stronger than the material of parts 10 a and 10b, at least the material forming determinant assembly alignment holes 12a and 12 b. In some embodiments, center pin 110 is formed from ahardened steel (e.g., medium carbon steel or high carbon steel). Thematerial of parts 10 a and 10 b depends on the application and may bemetal (e.g., aluminum, titanium), composite (e.g., carbon fiber),plastic, and the like.

FIG. 8C is a schematic illustration of self-retractable centeringassembly 100 and parts 10 a and 10 b at the beginning of operation 720,while FIG. 8D is a schematic illustration of the same component afteroperation 720 is completed. After completing operation 720, parts 10 aand 10 b are aligned. Specifically, after inserting center pin 110 intofirst determinant assembly alignment hole 12 a and second determinantassembly alignment hole 12 b, center axis 14 a of first determinantassembly alignment hole 12 a coincides with center axis 14 b of seconddeterminant assembly alignment hole 12 b as, for example, schematicallyshown in FIG. 8D. Parts 10 a and 10 b may be fixed in the aligned stateby various means, e.g., internal clamps, fasteners, welding, gluing, andother like methods.

Method 700 may proceed with retracting center pin 110 from firstdeterminant assembly alignment hole 10 a and from second determinantassembly alignment hole 10 b during operation 730. Different stages ofretracting operation 730 are schematically shown in FIGS. 8D-8F.Specifically, FIG. 8D illustrates center pin 110 still fully extendedand inserted into first determinant assembly alignment hole 10 a andfrom second determinant assembly alignment hole 10 b, and FIG. 8Fillustrates center pin 110 still fully retracted and sufficientlyremoved from first determinant assembly alignment hole 10 a and fromsecond determinant assembly alignment hole 10 b. At this stage, shown inFIG. 8F, center pin 110 is not supported by parts 10 a and 10 b and maybe further pulled away without rotating drive component 130 relative tocenter pin 110 as, for example, schematically shown in FIG. 8G.

Retracting operation 730 comprises rotating drive component 130 relativeto center pin 110 as shown by block 732. The rotation during retractingoperation 830 may be around center axis 119 of center pin 110. Thisrotation causes center pin 110 to slide relative to puller bushing 120as schematically shown by block 734. Puller bushing 120 may be supportedaxially during operation 730 as schematically shown by block 736. Inother words, puller bushing 120 may not move along center axis 119 withrespect to first part 10 a and second part 10 b during operation 730.More specifically, puller bushing 120 may be pressed against first part10 a while retracting center pin 110 as schematically shown in FIG. 8Eand by block 737 in FIG. 7.

In some embodiments, rotating drive component 130 relative to center pin110 during operation 730 comprises supporting puller bushing 120rotationally as shown by optional block 738. In other words, pullerbushing 120 may not rotate around center axis 119 with respect to firstpart 10 a and second part 10 b during operation 730. For example, pullerbushing 120 may be supported by an operator using a wrench or some othersuitable tool. In some embodiments, drive component 130 may be rotatedrelative to puller bushing 120 during operation 730. Puller bushing 120may not rotate relative to center pin 110.

In some embodiments, center pin 110 does not rotate within firstdeterminant assembly alignment hole 12 a relative to first part 10 a orwithin second determinant assembly alignment hole 12 b relative tosecond part 10 b as center pin 110 is being retracted from firstdeterminant assembly alignment hole 12 a and second determinant assemblyalignment hole 12 a. Furthermore, puller bushing 120 may be stationaryrelative to first part 10 a as center pin 110 being retracted.Specifically, puller bushing 120 may not rotate relative to first part10 a.

Alternatively, puller bushing 120 rotates relative to first part 10 a.In these embodiments, center pin 110 may also rotate within firstdeterminant assembly alignment hole 12 a relative to first part 10 a orwithin second determinant assembly alignment hole 12 b relative tosecond part 12 b as center pin 110 is being retracted. Center pin 110may also rotate relative to first part 10 a at a different speed or in adifferent direction than drive component 130. In some embodiments, drivecomponent 130 does not rotate relative to first part 10 a.

In some embodiments, after retracting center pin 110 from determinantassembly alignment holes 12 a, method 700 proceeds with increasing sizeof first determinant assembly alignment hole 12 a and second determinantassembly alignment hole 12 b as shown by optional block 740 in FIG. 7.The original boundaries of first determinant assembly alignment hole 12a and second determinant assembly alignment hole 12 b are shown in FIG.8H with dashed lines.

In same or other embodiments, after retracting center pin 110, method700 proceeds with installing fastener 800 into first determinantassembly alignment hole 12 a and second determinant assembly alignmenthole 12 b as shown by optional block 750 in FIG. 7. FIG. 8I illustratestwo aligned parts 10 a and 10 b with fastener 800 installed into firstdeterminant assembly alignment hole 12 a and second determinant assemblyalignment hole 12 b. It should be noted that parts 10 a and 10 b mayhave multiple sets of determinant assembly alignment holes 12 a and 12b. One or more of these sets (but not all) may be used for aligningparts 10 a and 10 b using one or more self-retractable centeringassemblies 100. Specifically, center pin 110 of one of self-retractablecentering assemblies 100 may be inserted into each set of determinantassembly alignment holes 12 a and 12 b used for alignment. While one ormore center pins 110 remain inserted in respective determinant assemblyalignment holes 12 a and 12 b, the remaining ones of determinantassembly alignment holes 12 a and 12 b may be used to secure parts 10 aand 10 b in their aligned state. Specifically, fastener 800 may beinstalled into each of these sets of determinant assembly alignmentholes 12 a and 12 b. Optionally, the size of these determinant assemblyalignment holes 12 a and 12 b may be increased prior to installingfastener 800. Once parts 10 a and 10 b are secured in their alignedstate, center pins 110 of self-retractable centering assemblies 100 maybe retracted from determinant assembly alignment holes 12 a and 12 bused for alignment. Additional fasteners 800 may be then installed intothese determinant assembly alignment holes 12 a and 12 b.

In some embodiments, determinant assembly alignment holes 12 a and 12 bare used for aligning parts 10 a and 10 b using one or moreself-retractable centering assemblies 100. Specifically, center pin 110of one of self-retractable centering assemblies 100 may be inserted intoeach set of determinant assembly alignment holes 12 a and 12 b. Whileone or more center pins 110 remain inserted in respective determinantassembly alignment holes 12 a and 12 b, additional holes are formed inparts 10 a and 10 b. These additional holes are used to secure parts 10a and 10 b in their aligned state. Specifically, fastener 800 may beinstalled into each of these additional holes. It should be noted thatthese holes are formed and the fasteners are installed in these holeswhile parts 10 a and 10 b are remain aligned with self-retractablecentering assemblies 100. Once parts 10 a and 10 b are secured in theiraligned state by installing the fasteners into the additional holes,center pins 110 of self-retractable centering assemblies 100 may beretracted from determinant assembly alignment holes 12 a and 12 b usedfor alignment. Parts 10 a and 10 b are retained in the aligned state bythe fasteners. In some embodiments, additional fasteners 800 may be theninstalled into determinant assembly alignment holes 12 a and 12 bpreviously used for aligning.

Examples of Aircraft Application

Examples of the disclosure may be described in the context of anaircraft manufacturing and service method 1100 as shown in FIG. 9 andaircraft 1102 as shown in FIG. 10. During pre-production, illustrativemethod 1100 may include specification and design 1104 of the aircraft1102 and material procurement 1106. During production, component andsubassembly manufacturing 1108 and system integration 1110 of aircraft1102 take place. For example, self-retractable centering assembly 100may be used during operation 1108 or operation 1110. Thereafter,aircraft 1102 may go through certification and delivery 1112 to beplaced in service 1114. In some embodiments, self-retractable centeringassembly 100 may be used during operation 1112 or operation 1114. Whilein service by a customer, aircraft 1102 is scheduled for routinemaintenance and service 1116 (which may also include modification,reconfiguration, refurbishment, and so on. Self-retractable centeringassembly 100 may be used during these later operations as well.

Each of the processes of illustrative method 1100 may be performed orcarried out by a system integrator, a third party, and/or an operator(e.g., a customer. For the purposes of this description, a systemintegrator may include, without limitation, any number of aircraftmanufacturers and major-system subcontractors; a third party mayinclude, without limitation, any number of vendors, subcontractors, andsuppliers; and an operator may be an airline, leasing company, militaryentity, service organization, and so on.

As shown in FIG. 10, aircraft 1102 produced by illustrative method 1100may include airframe 1118 with a plurality of high-level systems 1120and interior 1122. Examples of high-level systems 1120 include one ormore of propulsion system 1124, electrical system 1126, hydraulic system1128, and environmental system 1130. Any number of other systems may beincluded. Although an aerospace example is shown, the principlesdisclosed herein may be applied to other industries, such as theautomotive industry. Accordingly, in addition to aircraft 1102, theprinciples disclosed herein may apply to other vehicles, e.g., landvehicles, marine vehicles, space vehicles, etc.

Apparatus and methods shown or described herein may be employed duringany one or more of the stages of the aircraft manufacturing and servicemethod 1100. For example, components or subassemblies corresponding tocomponent and subassembly manufacturing 1108 may be fabricated ormanufactured in a manner similar to components or subassemblies producedwhile aircraft 1102 is in service. Also, one or more aspects of theapparatus, method, or combination thereof may be utilized duringoperations 1108 and 1110, for example, by substantially expeditingassembly of or reducing the cost of aircraft 1102. Similarly, one ormore aspects of the apparatus or method realizations, or a combinationthereof, may be utilized, for example and without limitation, whileaircraft 1102 is in service, e.g., maintenance and service 1116.

CONCLUSION

Different examples of the apparatus(es) and method(s) disclosed hereininclude a variety of components, features, and functionalities. Itshould be understood that the various examples of the apparatus(es) andmethod(s) disclosed herein may include any of the components, features,and functionalities of any of the other examples of the apparatus(es)and method(s) disclosed herein in any combination, and all of suchpossibilities are intended to be within the spirit and scope of thepresent disclosure.

Many modifications of examples set forth herein will come to mind to oneskilled in the art to which the present disclosure pertains having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings.

Therefore, it is to be understood that the present disclosure is not tobe limited to the specific examples illustrated and that modificationsand other examples are intended to be included within the scope of theappended claims. Moreover, although the foregoing description and theassociated drawings describe examples of the present disclosure in thecontext of certain illustrative combinations of elements and/orfunctions, it should be appreciated that different combinations ofelements and/or functions may be provided by alternative implementationswithout departing from the scope of the appended claims. Accordingly,parenthetical reference numerals in the appended claims are presentedfor illustrative purposes only and are not intended to limit the scopeof the claimed subject matter to the specific examples provided in thepresent disclosure.

1. A self-retractable centering assembly comprising: a center pin,comprising a center axis; a puller bushing, comprising a cavity, thecenter pin protruding through the puller bushing, the center pin beingslidable relative the puller bushing along the center axis of the centerpin; a drive component, rotatably coupled to the puller bushing, thecenter pin being slidable relative to the drive component along thecenter axis of the center pin.
 2. The self-retractable centeringassembly of claim 1, wherein the center pin comprises a threadedportion, threadably engaging the drive component such that rotation ofthe drive component relative to the center pin and around the centeraxis of the center pin slides the center pin relative to the drivecomponent and to the puller bushing.
 3. The self-retractable centeringassembly of claim 1, wherein the center pin is non-rotatable relative tothe puller bushing.
 4. The self-retractable centering assembly of claim3, further comprising a coupling component non-rotatably engaging thepuller bushing and the center pin.
 5. The self-retractable centeringassembly of claim 3, wherein the center pin comprises a collar disposedwithin the cavity such that both the collar and the cavity havenon-circular cross-sectional shapes within a plane perpendicular to thecenter axis of the center pin.
 6. The self-retractable centeringassembly of claim 3, further comprising a slot key protruding into aslot of the center pin and into a sliding slot of the puller bushing. 7.The self-retractable centering assembly of claim 3, further comprising atransverse pin protruding through the center pin in a directionperpendicular to the center axis of the center pin and extending awayfrom the center pin and into two slots of the puller bushing.
 8. Theself-retractable centering assembly of claim 3, further comprising asliding planar surface of the center pin and a protrusion fixed relativethe puller bushing, wherein the sliding planar surface extends parallelto the center axis of the center pin.
 9. The self-retractable centeringassembly of claim 1, further comprising a limiter, disposed within thecavity of the puller bushing and limiting a sliding distance of thecenter pin relative to the puller bushing.
 10. The self-retractablecentering assembly of claim 9, wherein the limiter is selected from thegroup consisting of a stop nut threadably engaging a threaded portion ofthe center pin, a collar of the center pin, a slot key protruding into aslot of the center pin, a Woodruff key protruding into a slot of thecenter pin, a transverse pin protruding through the center pin in adirection perpendicular to the center axis of the center pin andextending away from the center pin, and a combination of a slidingplanar surface of the center pin and a protrusion fixed relative thepuller bushing, and wherein the sliding planar surface extends parallelto the center axis of the center pin.
 11. A method of aligning a firstpart relative to a second part, the method comprising: retracting acenter pin of a self-retractable centering assembly from a firstdeterminant assembly alignment hole of the first part and from a seconddeterminant assembly alignment hole of the second part, retracting thecenter pin comprising rotating a drive component of the self-retractablecentering assembly relative to the center pin.
 12. The method of claim11, wherein the drive component is rotated around a center axis of thecenter pin.
 13. The method of claim 11, wherein rotating the drivecomponent relative to the center pin causes the center pin to advanceaxially relative to the drive component and relative to the first partand the second part.
 14. The method of claim 11, wherein retracting thecenter pin comprises pressing a puller bushing against the first part,the center pin extending through the puller bushing, the puller bushingbeing positioned between the drive component and the first part.
 15. Themethod of claim 14, wherein retracting the center pin comprises slidingthe center pin relative to the puller bushing.
 16. The method of claim14, wherein, while sliding the center pin relative to the pullerbushing, the center pin does not rotate relative to the puller bushing.17. The method of claim 11, wherein rotating the drive componentrelative to the center pin comprises rotationally supporting a pullerbushing.
 18. The method of claim 11, wherein the center pin does notrotate within the first determinant assembly alignment hole relative tothe first part or within the second determinant assembly alignment holerelative to the second part as the center pin is being retracted fromthe first determinant assembly alignment hole and from the seconddeterminant assembly alignment hole.
 19. The method of claim 18, whereina puller bushing of the self-retractable centering assembly isstationary relative to the first part while retracting the center pin.20. The method of claim 18, wherein a puller bushing of theself-retractable centering assembly rotates relative to the first partwhile retracting the center pin.